Application of treatment agents to ingot moulds

ABSTRACT

MOLTEN METAL MAY BE TREATED DURING CASTING, E.G. TO FORM INGOTS, BY PLACING ON THE BASE OF THE INGOT MOULD PRIOR TO CASTING A TREATMENT AGENT IN A COMBUSTIBLE CONTAINER, THERE BEING AN AIR SPACE BETWEEN THE TREATMENT AGENT IN THE CONTAINER AND THE BASE OF THE MOULD.

F. A. DUHEM Sept. 20, 1971 APPLICATION OF TREATMENT AGENTS TO INGOT MOULDS Filed Sept. 4, 1968 2 Sheets-Sheet 1 Sept. 20, 1971 DUHEM 3,605,857

APPLICATION OF TREATMENT AGENTS T0 INGO'I MOULDS Filed Sept. 4, 1968 2 Sheets-Shoot 2 FIG.4

United States Patent 3,605,857 APPLICATION OF TREATMENT AGENTS T0 INGOT MOULDS Francois Adrien Duhem, Pres-de-Sedan, France, assignor to Foseco International Limited, Birmingham, England Filed Sept. 4, 1968, Ser. No. 757,294 Int. Cl. B22d 27/18, 27/20 US. Cl. 16459 2 Claims ABSTRACT OF THE DISCLOSURE Molten metal may be treated during casting, e.g. to form ingots, by placing on the base of the ingot mould prior to casting a treatment agent in a combustible container, there being an air space between the treatment agent in the container and the base of the mould.

The present invention relates to the application of treatment agents to ingot moulds.

Metal ingots are produced by teeming molten metal into ingot moulds, either by top-pouring or bottom-pouring. In the former case, molten metal is merely tapped from a ladle positioned directly above the open top of the mould whilst, in the latter case, molten metal enters the mould through an opening in the base via a runner system.

'In the casting of molten steel to form ingots, it is current practice to apply to the ingot moulds, before teeming, a fluxing and/or lubricating composition which will exert a cleansing action on the metal cast therein and impart an improved surface finish to the cast ingot. These compositions may be either applied to the mould walls, or may be placed on the base of the mould. In this latter case, when teeming commences, the composition becomes fluid and forms a layer on top of the rising molten metal surface. This layer serves to protect the exposed molten metal surface against oxidation and contacts the walls of the mould causing a thin layer to be left between the cast metal and the mould wall. Many flux compositions have been used for this purpose, these usually being based upon fly ash, sodium carbonate, siliceous or aluminous materials, fluorides, lime, etc., or mixtures of these.

Treatment of the above nature has allowed the production of ingots of considerably improved quality but certain disadvantages are encountered, particularly with bottompoured ingots. These arise, mainly in the early part of the teeming operation, from the fact that metal enters through the base of the mould under the influence of such considerable metallostatic pressure that it behaves like a fountain. The upward thrust easily penetrates any layer of fluxing composition, allowing droplets of metal to acquire an oxide coating by exposure to the atmosphere above the flux layer and possibly begin to solidify before impinging on the lower parts of the walls and the base member of the ingot mould which thus may become severely worn. Furthermore, the oxidised droplets and unmelted flux composition may become entrapped as inclusions in the lower part of the ingot.

We have now discovered that these disadvantages associated with bottom poured ingots may be overcome by applying the fluxing and/or lubricating compositions in a container designed to withstand the initial upsurge of molten metal.

According to the present invention there is provided a method of preparing a metal casting mould for use in the casting of metal therein, which comprises locating onthe base of the mould a combustible container holding 3,605,857 Patented Sept. 20, 1971 an additive substance adapted to facilitate the casting of the molten metal or modify the characteristics of the molten metal, the said container being so shaped as to leave an air space between itself and the base of the mould.

The combustible container preferably takes the form of a box constructed of cardboard or similar material. Such materials, although combustible, carbonise in contact with molten metal and are capable of retaining their shape for a sufficient period .to contain the initial fountain of molten metal. The box is generally open, and may be used to store the additive composition prior to use.

In order to provide an airspace below the box containing the additive composition, the side members of the box may extend downwardly below its base. Alternatively, the closure flaps of the box may be folded outwardly and then downwardly to constitute integral support members to support the body of the box a short way above the base of the ingot mould.

Preferably the support is provided by external side members of dimensions slightly less than the internal dimensions of the mould at its base, thus ensuring a loose fit against the mould walls. These side members serve to protect the bottom of the walls of the mould from erosion by the molten metal at the commencement of teeming. In order to enhance this protective action, as well as to increase the support given by the box to the additive composition, the underside of the box may be provided with additional members or a coil of corrugated or plain cardboard. Furthermore, the combustible container may be treated or impregnated with fire-retardents, such as sodium silicate, etc. to prolong the period during which it will retain its shape.

The invention is illustrated in the accompanying drawings which show:

FIG. 1: a cutaway view of a box for holding additive;

FIGS. 2. and 3: under views of boxes having alternative support wall configurations;

FIG. 4: a perspective view of a two-part additive support box.

In FIG. 1, the box consists of a tray having a base 1, dividing walls 2 and side walls 3. The tray is placed facing down as shown and walls 3 folded round and up to the position shown in the diagram to constitute an open container in which mould additive composition may be placed.

[In FIG. 4 the box consists of an open case S which is placed in the base of the ingot mould. A tray 6 containing the mould additive composition is then lowered into the case 5 and rests on staples mounted in the corners of case 5 half way up the side thereof.

I claim as my invention:

1. In a method of preparing a metal casting mould for use in the casting of metal by bottom pouring therein, the step of locating on the base of the mould a combustible box constructed of cardboard and holding an additive selected from the group consisting of substances adapted to modify the characteristics of the molten metal, said box being provided with closure flaps hingeably connected to its upper edges and folded outwardly and then downwardly to constitute supports extending below the base level of the box on which the box can rest so as to leave an air space between itself and the base of the mould.

2. A metal casting mould assembly which comprises a metal casting mould adapted for bottom pouring having located therein and resting on its base a combustible box constructed of cardboard and holding a substance known per se selected from the group consisting of substances for use in facilitating the casting of molten metal and substances for modifying the characteristics of molten metal, said box being provided with closure flaps hingeably connected to its upper edges and folded outwardly and then downwardly to constitute supports extending below the base level of the box on which the box can rest so as to leave an air space between itself and the base of the mould.

References Cited UNITED STATES PATENTS 2,979,793 4/1961 Wilson et a1. 16459 1,166,167 12/1915 Woods 164-58 FOREIGN PATENTS US. Cl. X.R. 

